Ibrahim Aden & Fardowsa Hanshi

BBC News, Mogadishu & Nairobi

A Ugandan military helicopter with eight people on board has crashed at the main international airport in Somalia's capital, Mogadishu, an aviation official has told the BBC.

The state-run news agency reported that a fire broke out after the helicopter crashed at the Aden Adde International Airport, but it had been quickly contained by the emergency services. Video footage showed plumes of smoke rising from the airport.

"We heard the blast and saw smoke and flames over a helicopter. The smoke entirely covered the helicopter," Farah Abdulle, one of the airport staff, told Reuters news agency.

The cause of the crash and casualty figures are unclear.

The head of the Somali Civil Aviation Authority, Ahmed Maalim, told the BBC that the helicopter had come down in the airport's military section after flying in from the Balidogle airbase in the Lower Shabelle region, about 90km (56 miles) north-west of Mogadishu.

He said that an investigation was under way to establish the cause of the crash.

Ugandan troops are part of an 11,000-strong African Union (AU) force helping the government fight the al-Qaeda-linked al-Shabab group, which has been waging a brutal insurgency in Somalia for more than two decades.

The crash delayed the departure of a Turkish Airlines passenger plane, but domestic flights continued to operate normally.